Factory installed DC to DC charger

[Geronimo John]

5 hours ago, jd1923 said:

An interesting test would be to see @Geronimo John's number with and without the hitch connected running the truck at idle. It appears the frame ground is helping and without it charge numbers should drop. Another good test would be to see improvement after adding the additional cabling to the alternator. Make sure you have purchased a HO alternator which I believe everybody here has done.

JD: Good ideas for my Phase 2 efforts.  Phase 1 is to adjust the parameters and add cooling fans. That Snackchaser 3% loss per a few degrees of temp rise of the Orion 30 amp unit was an eyeopener!

If the numbers don't come up to something close to 28 amps to my Battleborns, then I'll circle back to your two suggestions.  Both have merit.  But they also are not pretty much free as what Snackchaser suggested!   🙂

I would however modify your "with and without the hitch connected" test.  To also include disco the Anderson Chains, Safety Chains, 7 Pin Connection, and for grins the emergency safety cable for the Dexter's.   Basically severing all metallic paths between TV and OE2 except my 4 AWG cables for the DC to DC system.   But then I suspect that's what you were suggesting to do.  

GJ

[jd1923]

Asking @Snackchaser, @Geronimo John and @Coddiwomple what did you use for fuses in your DC-DC charging systems? The wiring diagram shows fuses on B+ at the both truck and trailer batteries.

The user manual for the Victron 50A DC-DC charger states the fuse should be 60A or 70A. What do you suggest, or what did you install? 60A would be better protection but would not want to blow a fuse during a short surge. I want to go with ANL or other fuse type and not a circuit breaker.

[Coddiwomple]

1 hour ago, jd1923 said:

Asking @Snackchaser, @Geronimo John and @Coddiwomple what did you use for fuses in your DC-DC charging systems?

I used the following that were recommended by Artek.
1. Blue Seas MRBF Terminal Fuse Block and a MRBF 60 amp Fuse.
2. Blue Seas Series 187 Surface Mount Thermal Circuit Breaker 60 amp.
I have attached photos.

[Snackchaser]

3 hours ago, jd1923 said:

Asking @Snackchaser, @Geronimo John and @Coddiwomple what did you use for fuses in your DC-DC charging systems? 

I also used a Blue Seas MRBF 60 amp fuse, and I added a redundant 60 amp breaker just as a disconnect switch.

The Orion output has a #7720 Blue Seas 60 amp fuse block, rather than a breaker.

Just as a FYI:  A breaker has polarity so it only protects the wire on the load side.   In this unique application, you would have to decide if the breaker will protect the wire from the massive Oliver battery current potential, or from the 50 amp Orion charger potential.  Whereas a fuse has no polarity, it protects the wire from both potentials.

[Geronimo John]

3 hours ago, Coddiwomple said:

I used the following that were recommended by Artek.
1. Blue Seas MRBF Terminal Fuse Block and a MRBF 60 amp Fuse.
2. Blue Seas Series 187 Surface Mount Thermal Circuit Breaker 60 amp.
I have attached photos.

Ditto.  Just make sure you have the head room under hood for them.  

GJ

[Tom and Doreen]

10 hours ago, Snackchaser said:

I also used a Blue Seas MRBF 60 amp fuse, and I added a redundant 60 amp breaker just as a disconnect switch.

 

 

That's a really clean installation, great work!  One word of caution though is that  manual disconnecting / connecting with an active load applied can cause contact pitting and heating of the contacts in breakers of this type.  A heavy duty marine spec. switch with larger contact areas would also fit the bill since the circuit breaker is redundant in this application. 

[jd1923]

19 hours ago, Snackchaser said:

A breaker has polarity so it only protects the wire on the load side.   In this unique application, you would have to decide if the breaker will protect the wire from the massive Oliver battery current potential, or from the 50 amp Orion charger potential.  Whereas a fuse has no polarity, it protects the wire from both potentials.

I always understood this in Residential and Commercial AC power panels, but did not realize this in DC circuits until recently. There are no breakers in an automobile or truck, where is my experience. When I relocated ALL the breakers and fuses from under the streetside bed to the rear dinette seat, this became obvious from the terminal markings on all DC breakers. OTT had wired the 40A breaker in our hull, powering the rear positive bus (leveler jacks and more attached to this bus) in the wrong direction.

After all of your excellent feedback, I decided to go with MRFB fuses on both sides vs. ny sort of DC breaker> Blue Seas is the gold standard! However, their fuse today are made in Mexico. I found this company, made in South Bend IN, USA with a 4.7 Amazon rating (not easy to achieve) 

18 hours ago, Geronimo John said:

Just make sure you have the head room under hood for them.  

NP, I have a good 4" above the starter batteries in my old Dodge! Also have nothing but room above the positive bus that connects all solar chargers, etc. 

[Teaney Hull 292]

On 12/31/2024 at 4:10 AM, Snackchaser said:

Geez, I’m jealous!  If for not having to upsize the cable, I’d probably ditch my 30 amp for the 50 too!  Good on you for getting your total length down to 60’.   My ground is connected to the battery and I was closer to 90’ total with the 2500 RAM extended cab.  Have you done a wire size calculation for 50 amps at 60 feet?   #4 AWG is small for such length.

You got me thinking about using the truck frame for a ground, because logically it should be included in the wire size calculation.  It begs the question:  What is the frame resistance?  I couldn’t help myself, I had to try and figure it out. . .  in the wet cold dark.

Without an ohm meter that can measure such low frame resistance, I measured the voltage drop across an 88 ohm relay coil instead.  First measurement was through the relay and a jumper cable.  The second measurement included a loop from the jumper cable back through the truck frame.  After subtracting the jumper cable voltage drop, the frame resistance was calculated at 0.00295 ohms.   Given the resistance of #4 AWG is 0.000242 ohms per foot, the frame is equivalent to 12’ of #4 cable.  Of course there are many margins for error, but I think it’s a fair approximation.   

So it’s okay to use the frame as a ground, but it's prudent to add the frame resistance to your 60’ length when calculating wire size.

BTW, who is your supplier for the TEMCo wire if you don’t mind?  I used BatteryCablesUSA in the past, specifically their jumper cable which I noticed Oliver used for the solar panel.  It was comparatively inexpensive a year ago, and has doubled since.

I hope this helps you out.  Cheers!  Geoff

Love reading this Forum and seeing how smart guys like you are. Thanks for doing this. 

[jd1923]

23 hours ago, Tom and Doreen said:

One word of caution though is that  manual disconnecting / connecting with an active load applied can cause contact pitting and heating of the contacts in breakers of this type.  A heavy duty marine spec. switch with larger contact areas would also fit the bill since the circuit breaker is redundant in this application. 

Is a switch needed in the DC-DC charger installation? I'm going with fuses vs. breakers. Is it OK to merely connect and disconnect the Anderson SB175 pole connector at the truck-trailer connection? I would assume engine off would be better when connecting, starter battery present of course but not the extra current of a running alternator. When the connection is open the Orion DC-DC charger should go into a sleep state. This is how the the Victron MPPT SC works. It's always wired ON. The app shows zero voltage and current until I plug in the solar suitcase. I'm hoping to leave it wired ON. I purchased the environmental boots pictured above which keep the Anderson connectors insulated, dust and waterproof.

I meant to list this in my previous post. These are the MRBF fuses I purchased from South Bend: https://www.amazon.com/dp/B0BR4X7ZP5?ref=fed_asin_title&th=1

[Coddiwomple]

18 minutes ago, jd1923 said:

Is a switch needed in the DC-DC charger installation? I'm going with fuses vs. breakers. Is it OK to merely connect and disconnect the Anderson SB175 pole connector at the truck-trailer connection? I would assume engine off would be better when connecting, starter battery present of course but not the extra current of a running alternator.

I actually asked Artek these same questions and was told that a switch is not needed. Additionally, they said connecting and disconnecting should be done (as a good practice) when the engine is off and no charge current coming from alternator. 

[Snackchaser]

4 hours ago, Coddiwomple said:

I actually asked Artek these same questions and was told that a switch is not needed. Additionally, they said connecting and disconnecting should be done (as a good practice) when the engine is off and no charge current coming from alternator. 

True. . . but they were terribly misleading because the circuit is energized directly from the battery, regardless if the alternator is charging or not.   Think of it like a jumper cable connected to the battery, if you were to brush the red cable against any grounded surface of the vehicle then you're going to have big sparks like a welder . . . before any thermal fuse will blow.  

A circuit fused at 60 amps has significant potential and I think it would be somewhat negligent not to have a quick and easy means to disconnect it, as is the law in other applications.  It’s straight off the battery, always energized, running the length of the vehicle, with a connector exposed on the rear bumper.  Most mechanics wouldn’t have any idea what it is, and may not take precautions to avoid it.  

I love  @Tom and Doreen idea of using a high amperage switch instead of a breaker.  The switch is more obvious and it would do a better job at alerting someone of a high potential than might need to be shut-off.   I’m keenly aware that I’m too forgetful, and I may not always be around.

Cheers!  Geoff

[Coddiwomple]

4 hours ago, Snackchaser said:

the circuit is energized directly from the battery, regardless if the alternator is charging or not.

Thank you Geoff.  Correct.  They did say it is OK to connect and disconnect at the Anderson plug with the engine running, however, they felt it was a "good practice" to have the engine off.  Thanks for clarifying that.

[Geronimo John]

On 1/10/2025 at 7:23 AM, Coddiwomple said:

I actually asked Artek these same questions and was told that a switch is not needed. Additionally, they said connecting and disconnecting should be done (as a good practice) when the engine is off and no charge current coming from alternator. 

 

23 hours ago, Snackchaser said:

I love  @Tom and Doreen idea of using a high amperage switch instead of a breaker.

I'm with  both of you on this one.  I connect my TV to Ollie via a  Anderson 175 amp connector.  I have a 60 amp breaker at the TV battery.  Disconnect the Anderson only with the motor off as well.

I like having a breaker at the TV Battery.  That lets me not worry about potential damage to the under frame cables in transit threat when not in use.

I do not YET have a second 60 amp fuse on the Ollie end.  I assume it should ideally be mounted at the B+ terminal on Ollie.  I am assuming it's purpose to so kill power should a DC/DC charging B+ cable headed forward goes to ground.  Correct?.  

GJ

Edited January 11 by Geronimo John

[Tom and Doreen]

23 hours ago, jd1923 said:

Is a switch needed in the DC-DC charger installation? I'm going with fuses vs. breakers. Is it OK to merely connect and disconnect the Anderson SB175 pole connector at the truck-trailer connection? I would assume engine off would be better when connecting, starter battery present of course but not the extra current of a running alternator. When the connection is open the Orion DC-DC charger should go into a sleep state. This is how the the Victron MPPT SC works. It's always wired ON. The app shows zero voltage and current until I plug in the solar suitcase. I'm hoping to leave it wired ON. I purchased the environmental boots pictured above which keep the Anderson connectors insulated, dust and waterproof.

I meant to list this in my previous post. These are the MRBF fuses I purchased from South Bend: https://www.amazon.com/dp/B0BR4X7ZP5?ref=fed_asin_title&th=1

A switch would aid in troubleshooting / isolating the circuit / wiring should something go wrong but as you know these are beefy components / connections and limited space can be problematic. I would imagine that having the engine off and the fuse removed would accomplish the same thing should you need to isolate the circuit / wiring.  In honesty I've been thinking about doing a similar installation but as yet have not so I'm sure there are others here who have more knowledge / experience than me in this area.

[jd1923]

20 hours ago, Snackchaser said:

A circuit fused at 60 amps has significant potential and I think it would be somewhat negligent not to have a quick and easy means to disconnect it, as is the law in other applications.  It’s straight off the battery, always energized, running the length of the vehicle, with a connector exposed on the rear bumper.  Most mechanics wouldn’t have any idea what it is, and may not take precautions to avoid it.

Yeah, but so do the positive connections to the truck starter and alternator, and there are no fuses for protection in those circuits. That's why the first step in most auto service procedures is to disconnect battery ground. Only mechanic working on my truck, has been and will be me. 🤣

I want things up and ready vs. having switches under the hood or worse under the streetside bed!  (or even the dinette.) I don't mind the additional parasitic draw when chargers are on standby (I'll have 4 always ON, the MP2, two MPPT SCs and soon the Orion).  The Anderson Environmental Boot is enough protection for me.

Edited January 11 by jd1923
Added picture

[jd1923]

14 hours ago, Geronimo John said:

I like having a breaker at the TV Battery.  That lets me not worry about potential damage to the under frame cables in transit threat.

But when towing, you'll have it switched on anyway. Also, I would not run the positive cable "under frame." I will see if I can run it inside of the frame (safest location) or above the frame, up where the truck bed sits. There should be no chance of running over road debris that could damage the cable.

15 hours ago, Coddiwomple said:

They did say it is OK to connect and disconnect at the Anderson plug with the engine running, however, they felt it was a "good practice" to have the engine off.  Thanks for clarifying that.

Likely the Orion DC-DC charger would be fine connecting with engine ON or OFF. It allows input up to 17V and should have the internal protection to be connected to a running alternator, pushing 50 amps at 14.2V.

That being said, I would always have the engine off when connecting. This way the Orion would first be connected at a lower voltage (12.6V lead acid truck battery) and without immediate extra amperage to manage. The charger would wake up, take readings, become ready, and very likely would not start charging until after the truck is started, alternator generating considerable amperage at higher voltage.

I always turn the engine off anyway when hitching the trailer once the hitch ball is where it needs to be. I don't like diesel noise and fumes while connecting and with the addition of a DC-DC charger, there is just one more cable to connect!

[Geronimo John]

10 hours ago, Tom and Doreen said:

A switch would aid in troubleshooting / isolating the circuit

I agree.  But a switch has only and on/off function.  Better is a circuit breaker or a fuse.  Either provides protection to down range wiring in both the open and closed position.  If you only have a switch, and something damages the conductors going to Ollie, an on switch gives you no short circuit protection on the wires from the TV Battery to the Orion DC/DC unit.  

My preference to use a circuit breaker and not a fuse at the TV battery.  Quality fuses of this size and amperage typically are bolted in fuses.  Compared to a flip of a breaker, undoing the two fuse bolts, is far less convenient.... especially when you drop the washer or nut into the manifold and have to wait an hour for it to cool down to fetch with your fingers because you forgot to pack the magnet on a stick at home!  😞

GJ

Edited January 12 by Geronimo John
Cleaned up two awkward sentences.

[Tom and Doreen]

43 minutes ago, Geronimo John said:

I agree.  But a switch has only and on/off function. 

True.  I believe the installation does have a fuse already so a circuit breaker seemed redundant.  

[jd1923]

4 hours ago, Geronimo John said:

Compared to a flip of a breaker, undoing the two fuse bolts, is far less convenient...

Another component that can fail and adds resistance to the circuit. Most DC breakers are China made junk too, hard to find a quality DC breaker but quality fuses are readily available. There is really no maintenance required, no reason to disconnect the 12V+ to the rear bumper of the truck. Just push the Anderson SB175 to connect and pull it off when parked. I would not pop the hood to throw a breaker on/off each time. The Anderson connecter as shown above will be well insulated.

If I'm working on a truck electrical system, I will disconnect ground on the battery anyway (1/2" wrench on US trucks, 10mm on Jap trucks). I did the same with my 600AH Epoch LiFePO4 batteries. I wanted one straight 4/0 cable connection from batteries to the Victron MP2 inverter charger, no breakers or switches, but there is one 400A ANL fuse (Victron spec). I have not needed to disconnect it in the 6 months since it was installed and I don't see a need going forward (we do not put our Oliver in storage). I should be able to install the Orion DC-DC with the Oliver batteries connected, given my +tive bus installation. Whenever I need to, instead of opening up the battery bay, or worse uncover the Oliver basement to throw a switch, I will grab a 1/2" wrench and disconnect the battery ground cable.

[Geronimo John]

28 minutes ago, jd1923 said:

no reason to disconnect the 12V+ to the rear bumper of the truck

For your purposes that may well be true.  

But for at least one of us when we are not connected to Ollie, we like to go play where off road conditions sometimes involves stuff impacting our undercarriage, frame and floor panels.  Would like to avoid that, but stuff happens.  That puts our cables that are exposed at some risk.  I prefer to kill the breaker at the TV battery and not worry about it when doing so.  

Sure we could have run the cables thru the frame, but John Davies taught us that doing so we can not secure them from bouncing around.  Since the frame is welded, I am not so sure that they ground down any of those robot welds smooth so our cables would not be taking a slicing as we bounce around out there.  

Sure there is a price to pay for the power loss through breakers.  But I have come to terms with that loss as compared to the time of unbolting the fuse each time I go play.  So, I guess I'm the Flipper Camp and you are in the Screw It Camp.  Just the way it works out some days.  But the good news is that we both agree that circuit protection of those lines IS in fact a very important safety element of our DC to DC charging systems.  

You did mention not knowing of any quality breaker makers.  I don't know myself.  So let's ask!  After all, this sort of question was asked a few years ago and a fellow owner nicely introduced me to BlueSeas product lines.  So here goes?

Anybody know of a good quality circuit breaker for under hood install in the battery area that is rated at 60 amps?    

[Geronimo John]

4 hours ago, Tom and Doreen said:

True.  I believe the installation does have a fuse already so a circuit breaker seemed redundant.  

The Victron Orion installation requires circuit protection from both sides of the system.  One at the TV battery and another at the load side of the connection.  JD prefers two fuses and that works great for him.  I am in the Circuit Breaker camp on the TV side and a fuse like JD suggests on the Ollie end of those 4 AWG's. 

Of the two, I think the load end is the most important.  Reason is that if you have a direct short our Litho's easily generate more than 3X the power that the TV battery can.

The fuse sizing criterion includes:  Amps, Volts, and Potential Power.  Sure we could put a small fuse with a small 10 Ga wire on it.  But if short circuited, it would be blown away and certainly not contain the potential energy generated by the 1800 amps or more that three Battleborns can generate.  I would not want to even guess what those twin 360 AH Litho installs could put out but would bet they can melt 4/0 cables in two seconds.  Hence using quality fuses as JD suggested or a quality circuit breaker and fuse.  

[Geronimo John]

10 hours ago, jd1923 said:

Also, I would not run the positive cable "under frame."

Bad description above. Thanks for highlighting it.

I should said along the frame.  I want the frame to at least somewhat protect the cables during off roading. 

Also not stated is that Ford requires all such cables to be run in high temperature loom to keep their warranty.    

Thanks  GJ

Edited January 12 by Geronimo John